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What
does DALI stand for?
Digital Addressable Lighting Interface
Sounds
complicated - what is it? A protocol that provides flexibility in control
of fluorescent lighting.
With a
DALI based lighting system, dimming can be deployed throughout a property
to achieve energy savings of 30%-60% and give substantial flexibility,
occupier control and servicing benefits.
HOW
IT WORKS
The
term ‘digital network’ sounds complicated but most of the basic
hardware is standard issue - ballasts, lamps, controls, cabling etc.
The real difference is that the luminaire ballasts are networked to
a PC which enables bi-way communication. The PC
can instruct each ballast what to do, and the ballast can feedback
information regarding performance.
DALI
centred digital lighting networks are based on digital fluorescent
electronic ballasts operating linear T5 and T8 lamps and CFL’s.
Digital
ballasts and DALI interfaces are being designed for HID, incandescent and
low-voltage halogen systems.
Digital
ballasts "soft start" fluorescent lamps extending tube life; cut
the lamps out at end of life; systematically dim; and can start the lamps
at any point in the dimming range.
The
ballasts are connected to form a large lighting loop that can contain
multiple luminaires.
Digital
protocol allows simplified control wiring that provides greater
flexibility than traditional 0-10V analog systems. Each ballast in the
loop is given an ‘address’ by the PC so it can be individually
controlled or grouped in multiple configurations. The loop is then
connected to any type of DALI-compatible control device's.
Control
options include local wall-mounted controls that enable manual push-button
switching to select programmed dimming scenes; a computer for centralized
lighting control; local PCs for individual occupant control; and occupancy
sensors (PIR’s, Microwave sensors etc), photocells and other controls.
From a
central PC, the Facilities Manager can address each ballast in a building
or gang them in groups, then program each ballast or group to dim from
100% to 1% either on a scheduled basis or in direct response to prevailing
conditions, such as natural daylight.
The
lighting components feedback, providing information that can be used to
identify lamp and ballast failure and generate useful energy consumption
data. The nett benefits to the user are energy saving and
flexibility in control of light levels.
Our
thanks go to Craig DiLouie of the Lighting Controls Association for
sending us the article from which the above information was derived. |